An introduction to Apache Traffic Server. Leif Hedstrom December 2011

Transcription

1 An introduction to Apache Traffic Server Leif Hedstrom December 2011

2 Who am I? One of the drivers to open source Traffic Server (at Yahoo) Committer for Apache Traffic Server VP of Apache Traffic Server PMC ASF member Go Daddy s Principal Architect for Hosting +zwoop

3 History of Traffic Server Inktomi Traffic Server Yahoo Traffic Server Apache Traffic Server

4 Plenty of FOSS Proxy Servers

5 Features ATS HAproxy nginx Squid Varnish mod_proxy Worker Threads Y N N N Y Y Multi-Process N Y Y N Y Y Event-driven Y Y Y Y sometimes Y Plugin APIs Y N Y part Y Y Forward Proxy Y N N Y N Y Reverse Proxy Y Y Y Y Y Y Transp. Proxy Y Y N Y N N Load Balancer weak Y Y Y Y Y Persistent Cache Y N Y Y sorta Y ESI Y N N Y kinda N ICP soon N N Y N N Keep-Alive Y N Y Y Y Y SSL Y N Y Y N Y Pipeline Y N Y Y N Y

6 Mandatory useless benchmark 120,000" 100,000" Throughput) 80,000" 60,000" 40,000" 20,000" 0" ATS"2.1.9" Nginx"0.8.53" Varnish"2.1.5" Req"/"sec"

7 Less useless benchmark Throughput% 120,000# 100,000# 80,000# 60,000# 40,000# 20,000# 0# ATS#2.1.9# Nginx#0.8.53# Varnish#2.1.5# 4.0# 3.5# 3.0# 2.5# 2.0# 1.5# 1.0# 0.5# 0.0# Time%to%first%response% Req#/#sec# Latency#(ms)#

8 Intermediaries - Forward Proxy The browser (UA) is explicitly configured to use the FP server as a proxy GET HTTP/1.1 Web site A Browser Forward Proxy Web site B GET / HTTP/1.1 Host: c.com Web site C

9 Intermediaries - Reverse Proxy The reverse proxy has explicit rules for a.com, b.com and c.com. Other requests are (typically) denied GET / HTTP/1.1 Host: c.com Web site A Browser Reverse Proxy Web site B GET / HTTP/1.1 Host: c.com Web site C

10 Intermediaries - Intercepting Proxy There are no explicit configurations in browser of proxy. The transparent proxy intercepts HTTP requests, and proxies them to the destination. GET / HTTP/1.1 Host: c.com Web site A Browser Router or Firewall Intercepting Proxy GET / HTTP/1.1 Host: c.com Web site B Web site C

11 Web Cash? h4p://

12 No, Web Cache! h4p://

13 Common enemies of performance 3-Way handshake Congestion control DNS lookups

14 Common enemies of performance 3-Way handshake Congestion control DNS lookups

15 TCP 3-way Handshake SYN SYN ACK ACK Client Established Server

16 Common enemies of performance 3-Way handshake Congestion control DNS lookups

17 Congestion control #2 #1 #0 ACK #8 #3 ACK 3-8 #21... #9 Client ACK 9-21 Server

18 Common enemies of performance 3-Way handshake Congestion control DNS lookups

19

20 vs

21 The concurrency problem

22 Solution 1: Multithreading Single CPU Dual CPU Thread 1 Thread 1 Thread 2 Thread 2 Thread 1 Thread 3 Thread 1 Thread 3 Thread 3 Thread 3 Time Time

23 Problems with multi-threading "When two trains approach each other at a crossing, both shall come to a full stop and neither shall start up again until the other has gone." From Wikipedia, Illogical statute passed by Kansas legislation.

24 Solution 2: Event Processing Scheduled events Network events Disk I/O events Queue Event Loop Disk handler HTTP state machine Accept handler Can generate new events

25 Problems with event processors

26 Traffic Server threads model n threads per core m threads per disk ~10 threads Asynchronous event processor Asynchronous event processor... Asynchronous event processor Disk I/O thread Disk I/O thread... Disk I/O thread Accept threads (per port) Logging threads Various "admin" threads Shared Resources RAM cache Disk cache Reloadable Configs Stats, logs etc.

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28 plugin.config records.config partition.config hosting.config cache.config update.config ip_allow.config storage.config logs_xml.config parent.config remap.config icp.config

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30 records.config for reverse proxy CONFIG proxy.config.http.server_port INT 80 CONFIG proxy.config.cache.ram_cache.size INT 1G CONFIG proxy.config.cache.ram_cache_cutoff INT 1M CONFIG proxy.config.reverse_proxy.enabled INT 1 CONFIG proxy.config.url_remap.remap_required INT 1 CONFIG proxy.config.url_remap.pristine_host_hdr INT 0 CONFIG proxy.config.http.negative_caching_enabled INT 1 CONFIG proxy.config.http.negative_caching_lifetime INT 120 CONFIG proxy.config.http.cache.ignore_client_cc_max_age INT 1 CONFIG proxy.config.http.normalize_ae_gzip INT 1

31 records.config for reverse proxy CONFIG proxy.config.http.server_port INT 80 CONFIG proxy.config.cache.ram_cache.size INT 1G CONFIG proxy.config.cache.ram_cache_cutoff INT 1M CONFIG proxy.config.reverse_proxy.enabled INT 1 CONFIG proxy.config.url_remap.remap_required INT 1 CONFIG proxy.config.url_remap.pristine_host_hdr INT 0 CONFIG proxy.config.http.negative_caching_enabled INT 1 CONFIG proxy.config.http.negative_caching_lifetime INT 120 CONFIG proxy.config.http.cache.ignore_client_cc_max_age INT 1 CONFIG proxy.config.http.normalize_ae_gzip INT 1

32 records.config for forward proxy CONFIG proxy.config.http.server_port INT 8080 CONFIG proxy.config.cache.ram_cache.size INT 1G CONFIG proxy.config.cache.ram_cache_cutoff INT 1M CONFIG proxy.config.reverse_proxy.enabled INT 0 CONFIG proxy.config.url_remap.remap_required INT 0 CONFIG proxy.config.url_remap.pristine_host_hdr INT 0 CONFIG proxy.config.http.negative_caching_enabled INT 1 CONFIG proxy.config.http.negative_caching_lifetime INT 120 CONFIG proxy.config.http.cache.ignore_client_cc_max_age INT 1 CONFIG proxy.config.http.normalize_ae_gzip INT 1

33 remap.config examples map map reverse_map redirect regex_map map /

34 remap.config examples map map reverse_map redirect regex_map map /

35 remap.config examples map map reverse_map redirect regex_map map /

36 remap.config examples map map reverse_map redirect regex_map map /

37 remap.config examples map map reverse_map redirect regex_map map /

38 Some interesting features RAM: Optional compression Various compression levels supported Very fast (virtually no overhead using the faster algo) RAM: Several cache eviction algorithms CLFUS algorithm avoids the classic problem on an LRU during scans Disk: Supports various block sizes (SSD) Disk: Can be tuned for various object sizes Disk: No file system overhead (RAW disks)

39 Future directions Release early, and often Full IPv6 support NPN, SNI and other SSL improvements Improved memory management, support debug features in e.g. jemalloc and tcmalloc Optimizations for SSD ( stacked caches) More focus on plugins, and plugin APIs Hopefully a real load balancer plugin!

40 Was this a huge waste of time, or? h4p://

41 A versatile tool h4p:// 41

42 Yes, it s fast, ridiculously fast 42

43 A vibrant community! The Apache Software Foundation 43

44 Artur Bergman tells us if we re not using SSD drives, we re wasting our lives.

45 Artur Bergman tells us if we re not using SSD drives, we re wasting our lives. I d say, if you are not using a caching proxy, you re wasting your SSDs!

46 46

47 Contact me 47

48 records.config for reverse proxy CONFIG proxy.config.http.server_port INT 80 CONFIG proxy.config.cache.ram_cache.size INT 1G CONFIG proxy.config.cache.ram_cache_cutoff INT 1M CONFIG proxy.config.reverse_proxy.enabled INT 1 CONFIG proxy.config.url_remap.remap_required INT 1 CONFIG proxy.config.url_remap.pristine_host_hdr INT 0 CONFIG proxy.config.http.negative_caching_enabled INT 1 CONFIG proxy.config.http.negative_caching_lifetime INT 120 CONFIG proxy.config.http.cache.ignore_client_cc_max_age INT 1 CONFIG proxy.config.http.normalize_ae_gzip INT 1

49 Four Horseman of Bad Performance Data copies Context Switches Memory allocation Lock contention Avoid these!

50 Disk cache: Cyclone